Why Is Obama Keeping Secret Four Seconds of a Nixon-Era Tape?

After promising to be the “most transparent” in history, the Obama administration is still refusing to release four seconds of a recording that Richard Nixon’s chief of staff, H.R. Haldeman, made 42 years ago.

Ken Hughes, a University of Virginia researcher who’s studied Nixon-era tapes, requested in February that the snippet of the Jan. 12, 1973, discussion on “Vietnam Negotiations” be declassified.

Revealing what was said, however, “would reveal information that would impair U.S. cryptologic systems or activities,” National Security Agency spokeswoman Vanee Vines said in an e-mailed statement.